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Whisper Streaming with FastAPI and WebSocket Integration

This project extends the Whisper Streaming implementation by incorporating few extras. The enhancements include:

1. Efficient FastAPI Server with WebSocket Endpoint: Real-time speech-to-text transcription for browsers, web apps, or React Native, with audio chunks processed via FFmpeg async streaming process to ensure minimal latency.

2. Buffering preview: Enhances streaming feedback by displaying the unvalidated buffer content, allowing users to see live processing updates.

3. Javascript Client implementation: Functionnal and minimalist MediaRecorder implementation that can be copied on your client side.

4. MLX Whisper backend: Integrates the alternative backend option MLX Whisper, optimized for efficient speech recognition on Apple silicon.

Code Origins

This project reuses and extends code from the original Whisper Streaming repository:

• whisper_online.py: Contains code from whisper_streaming with the addition of the MLX Whisper backend for Apple Silicon, which is not present in the original repository.
• silero_vad_iterator.py: Originally from the Silero VAD repository, included in the whisper_streaming project.

Installation

1. Clone the Repository:

   git clone https://github.com/QuentinFuxa/whisper_streaming_web
   cd whisper_streaming_web
   

How to Launch the Server

1. Dependencies:

• Install required dependences :

  # Whisper streaming required dependencies
  pip install librosa soundfile
  
  # Whisper streaming web required dependencies
  pip install fastapi ffmpeg
  

• Install at least one whisper backend among:

  whisper
  whisper-timestamped
  faster-whisper (faster backend on NVIDIA GPU)
  mlx-whisper (faster backend on Apple Silicon)
  
  and torch if you want to use VAC (Voice Activity Controller)
  

• Optionnal dependencies

  # If you want to use VAC (Voice Activity Controller)
  torch
  
  # If you choose sentences as buffer trimming strategy
  mosestokenizer
  wtpsplit
  tokenize_uk # If you work with Ukrainian text
  
  # If you want to run the server using uvicorn (recommended)
  uvicorn
  

3. Run the FastAPI Server:

   python whisper_fastapi_online_server.py --host 0.0.0.0 --port 8000
   

   • --host and --port let you specify the server’s IP/port.
   • -min-chunk-size sets the minimum chunk size for audio processing. Make sure this value aligns with the chunk size selected in the frontend. If not aligned, the system will work but may unnecessarily over-process audio data.
   • For a full list of configurable options, run python whisper_fastapi_online_server.py -h

4. Open the Provided HTML:

   • By default, the server root endpoint / serves a simple live_transcription.html page.
   • Open your browser at http://localhost:8000 (or replace localhost and 8000 with whatever you specified).
   • The page uses vanilla JavaScript and the WebSocket API to capture your microphone and stream audio to the server in real time.

How the Live Interface Works

• Once you allow microphone access, the page records small chunks of audio using the MediaRecorder API in webm/opus format.
• These chunks are sent over a WebSocket to the FastAPI endpoint at /ws.
• The Python server decodes .webm chunks on the fly using FFmpeg and streams them into the whisper streaming implementation for transcription.
• Partial transcription appears as soon as enough audio is processed. The “unvalidated” text is shown in lighter or grey color (i.e., an ‘aperçu’) to indicate it’s still buffered partial output. Once Whisper finalizes that segment, it’s displayed in normal text.
• You can watch the transcription update in near real time, ideal for demos, prototyping, or quick debugging.

Deploying to a Remote Server

If you want to deploy this setup:

1. Host the FastAPI app behind a production-grade HTTP(S) server (like Uvicorn + Nginx or Docker). If you use HTTPS, use "wss" instead of "ws" in WebSocket URL.
2. The HTML/JS page can be served by the same FastAPI app or a separate static host.
3. Users open the page in Chrome/Firefox (any modern browser that supports MediaRecorder + WebSocket).

No additional front-end libraries or frameworks are required. The WebSocket logic in live_transcription.html is minimal enough to adapt for your own custom UI or embed in other pages.

Acknowledgments

This project builds upon the foundational work of the Whisper Streaming project. We extend our gratitude to the original authors for their contributions.